Movie 3

Polarization of the B cell MTOC polarizes towards anti-Ig-coated beads. A20 cells that had been transfected with GFP-α-tubulin were mixed with 4.5-μm diameter anti-IgG-coated beads. Time-lapse confocal microscopy was used to acquire images every 2.5 s between 3 min and 8 min after adding the beads to the cells. The video is played back at 40 frames per second (100X real time).